1. Field of the Invention
This invention relates to a laser delivery device, and more particularly to such delivery devices that a emit radially well directed emission pattern from the distal end of an optical fiber.
2. Prior Art Statement
Technological change in laser delivery devices is rapidly taking place in the laser medical field with the onset of minimally invasive procedures such as laser laparoscopy. The laparoscopist, a physician or surgeon who performs laparascopies, is often challenged with positioning the delivery device, i.e., the optical fiber(s), at angles radially to the laparoscope axis in order to irradiate the target perpendicularly. However, in many cases moving a laparoscope radially is very difficult or is impossible. As an alternative, the laparoscope, which is normally rigid, may have an adjustable fiber deflector called a bridge. The bridge may be adjusted at the proximal end causing radial movements to the distal end of the fibers. This adjustment is, however, limited by the bend radius of the fibers and/or the bridge device and cannot offer full capabilities. Therefore, techniques to emit radiation radially from the distal end of the fiber without bending are needed.
Reflecting tips secured on the distal fiber end, such as metal caps incorporating a mirror surface at a 45.degree. angle relative to the fiber axis are state of the art and have been used successfully in procedures such as lithotripsy with high pulse powered (Q-switched) Yttrium Aluminum Garnet Lasers.
For many surgical procedures requiring an even illumination (such as prostate treatment or photodynamic therapy) the point source-like radiation pattern from this known device is ill suited.
The state of the art devices used in photodynamic therapy incorporate a glue, i.e. epoxy, containing cap with scattering medium dispersed in it. These caps can produce a relatively homogeneous radial pattern. However, the output is diffuse and they are somewhat limited in power handling capability due to the limitations of the glue.
U.S. Pat. No. 5,019,075 to Spears et al describes a device for transluminal angioplasty of a stenosed artery with a diffusing area along an optical fiber created by removing the cladding and abrading the fiber core surface such that the fiber core surface is roughened. Diffuse radiation thus exits from the fiber circumference in random directions resulting in radiation energy being applied to the entire circumference of a selected region of an artery simultaneously. Although a given ray may indeed be reflected in a direction opposite to the roughened surface part, its direction will be as ambiguous as the roughened corner it is reflected on. The scattering media described by Spears would also create diffuse instead of well directed radiation patterns. This is unlike the present invention wherein a distinctly different, more controlled radiation pattern is emitted, specifically radially well directed (non diffuse) emission from an extended section of the fiber achieved by grooves having been formed in a predetermined pattern rather than mere roughening of the core surface.
In summary, the present state of the art for radial laser radiation delivery is restricted to either point sources (size of the source comparable to the fiber cross section) or to essentially diffuse radiators with limited power handling capabilities. U.S. Pat. No. 4,740,047 describes a point source type of device using a cut fiber with a reflective surface to deflect a beam for lateral application.
While methods to control the fiber tip temperature aimed at preventing damage to the distal tip of the laser delivery device have been described in U.S. Pat. No. 5,057,099 no control method has been described to prevent or limit damage to the tissue itself that seems applicable to treatments such as laser prostatectomy. Thus, while this recently issued patent allows for temperature control to optimize particular surgical or medical procedures, it does not address or satisfactorily resolve the need for proper lateral and radial delivery of laser beams to satisfy varied needs for varied procedures.
Thus, the prior art neither teaches nor renders obvious the present invention device set forth herein.